Compressed gas-blast circuit breaker

ABSTRACT

A hollow contact tube is provided in a compressed gas-blast circuit breaker in order to improve dielectric properties. The outlet ( 6 ) of said contact tube cooperates with a deflecting body ( 9 ) and is surrounded by a fixed substantially hollow cylindrical flow director ( 8 ).

CLAIM FOR PRIORITY

This application claims priority to German patent application no. 199 53560.4 which was filed on Nov. 3, 1999.

1. Technical Field of the Invention

The invention relates to a circuit breaker having a contact tube whichis hollow in order to carry away hot switching gases and bounds thebreaker gap, and whose outlet opening interacts with a stationary guidebody which is arranged at a distance from it.

2. Background of the Invention

A circuit breaker is described, for example, from Laid-OpenSpecification DE 39 04 439 A1. In the known arrangement, which isintended by way of example for 145 kV, the hot switching gases which areproduced in an arc in the breaker gap during a disconnection process arecarried away through the interior of a stationary contact tube. In thiscase, the hot switching gases are passed out of an outlet opening of thecontact tube to a stationary guide body. In the known arrangement, thecontact tube is arranged such that it is stationary, so that thedistance between the outlet opening and the guide body always remainsthe same, resulting in a constant, guided gas flow.

In order to achieve better dielectric strength for the breaker gap inthe circuit breaker, it is desirable for the distance between thecontact which bound the breaker gap to be made as large as possibleduring the disconnection process. In the known arrangement, theseparating gap can be enlarged during the disconnection process only bylengthening the operating travel of the moving contact.

SUMMARY OF THE INVENTION

The present invention discloses, in one embodiment, a circuit breakersuch that the separating gap is enlarged in the disconnected positionwithout lengthening the operating travel of the moving contact, andwithout adversely affecting the way in which the hot switching gases arecarried away.

In one aspect of the invention, a contact tube is guided such that itcan move axially, and the outlet opening is surrounded by a stationarynozzle-shaped flow guide in every position of the contact tube duringthe movement.

The capability of the contact tube to move axially makes it possible, ina simple manner, to enlarge the separating gap in the circuit breaker inthe disconnected position, with the stationary flow guide guiding theflow of hot switching gases independently of the position of the contacttube, and hence independently of its outlet opening. The guide body andthe nozzle-shaped flow guide are separated from one another by the samedistance. It is thus possible in conjunction with the guide body and theflow guide to ensure that the same boundary conditions are provided forthe flow of switching gases.

It is advantageously possible to provide for the flow guide to becomposed at least partially of an insulating material.

A further advantageous embodiment provides for the guide body to becomposed at least partially of an insulating material.

If the flow guide and the guide body, or one of the two, is at leastpartially comprised of a suitable insulating material, then it ispossible to reduce the electrical conductivity of the hot switchinggases as well, if, for example, PTFE is chosen, which releaseselectrically negative gas components under the influence of hotswitching gases. The flow guide and guide body may be formed from anumber of parts. In this case, it is possible for the individual piecesto be composed of different materials.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following text, the invention will be illustrated with referenceto a drawing, and the method of operation will be described in moredetail.

FIG. 1 shows the schematic design of an interrupter unit in a circuitbreaker.

FIG. 2 shows a drive-side detail of the interrupter unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the schematic design of an interrupter unit in ahigh-voltage circuit breaker. The connected position of the interrupterunit is shown underneath the line of symmetry, and the disconnectedposition is shown above the line of symmetry. The circuit breaker has afirst and a second arcing contact 1, 2, which are surrounded by a firstand a second rated current contact 3, 4. The first arcing contact 1 isin the form of a hollow contact tube. At its first free end, it has aninlet flow opening 5, while an outlet opening 6 is provided at itssecond free end. The drive for the circuit breaker is coupled by aswitching rod 7 to the second free end of the first arcing contact 1,and the movement of this drive moves the first arcing contact 1 and thefirst rated current contact 3 axially. An exxentially hollow-cylidricalflow guide 8 is arranged in the fixed position radially around theoutlet opening 6 of the first arcing contact 1. A conical guide body 9is arranged opposite the opening 10 of the flow guide 8.

The drive-side part of the interrupter unit is surrounded by an outletflow chamber 11. This outlet flow chamber 11 has outlet flow openings12. The wall of the outlet flow chamber 11 is comprised of anelectrically conductive material, which is used to conduct the electriccurrent. The interrupter unit of the high-voltage circuit breaker issurrounded by gas-tight encapsulation 13, which is filled with aninsulating gas, in particular SF₆.

A first and a second electrical connection 14, 15, as well as theswitching rod 7, are passed in a gas-tight manner through theencapsulation 13.

FIG. 2 shows a detail of the drive side of the interrupter unit, withthe position of the arrangement at the start of the disconnectionprocess being shown underneath the line of symmetry, and with theposition at the end of the disconnection process being shown above theline of symmetry.

The disconnection process starts with the separation of the ratedcurrent contacts 3, 4 and, as the disconnection process continues, thearcing contacts 1, 2 are separated, with an arc 16 being struck betweenthem. This arc 16 heats, expands and ionizes the quenching gas. In orderto quench the arc 16 and to remove the hot quenching gas from theseparating gap, additional quenching gas flows through the separatinggap. The additional flow through the separating gap can be produced, forexample, by a compression apparatus 18. Part of the quenching gas, whosepressure has been raised, is passed through the inlet flow opening 5 inthe first free end of the first arcing contact 1, and is carried away inthe interior of the first arching contact 1, by virtue of the tubularconfiguration of said first arcing contact 1. At the second free end ofthe first arcing contact 1 there is an outlet opening 6, which makes itpossible for the quenching gas to emerge from the first arcing contact1, which is in the form of a contact tube.

At the start of the disconnection movement, the outlet opening 6 in thesecond free end of the first arcing contact 1 projects entirely beyondthe flow guide 8 in the direction of the guide device 9. The hotswitching gases 17 emerge from the outlet opening 6 and are guided bythe flow guide 8 in the direction of the guide body 9. This prevents aradial, swirling outlet flow. As the disconnection movement continues,the first arcing contact 1 is moved in the direction of thefixed-position guide body 9. The outlet opening 6 in the second free endof the first arcing contact 1 likewise moves in the direction of theguide body 9, while the flow guide 8, which is mounted in a fixedposition, is not subjected to any movement. The interaction of the flowguide 8 and of the guide body 9 means that, despite the change in theposition of the outlet opening 6, the hot switching gas 17 is stilldirected onto the guide body 9. After passing the guide device 9, thequenching gas flows in the direction of the outlet flow opening 12 ofthe outlet flow chamber 11. The flow guide 8 ensures that the switchinggases 17 are carried uniformly, very largely independently of themovement of the contact tube, within the outlet flow chamber 11.

If the flow guide 8 and the guide body 9 are comprised of PTFE, theinsulating material is dissociated under the influence of the hottemperatures of the switching gas 17, with electrically negativecomponents being released from the insulating material. Theseelectrically negative components reduce the electrical conductivity toan advantagoues extent. The dielectric characteristics of the switch areimproved by the deliberate guidance of the quenching gas flow, and theenrichment of the quenching gas flow.

What is claimed is:
 1. A circuit breaker, comprising: a contact tubewhich is hollow, carries away hot switching gases and bounds a breakergap; and an outlet opening interacting with a stationary guide bodywhich is arranged at a distance therefrom and disposed at an endopposite from the breaker gap, wherein the contact tube is guided suchthat the contact tube can move axially, and the outlet opening issurrounded by a stationary nozzle-shaped flow guide in each position ofthe contact tube during the movement.
 2. The circuit breaker as claimedin claim 1, wherein the flow guide is at least partially comprised of aninsulating material.
 3. The circuit breaker as claimed in claim 1,wherein the guide body is at least partially comprised of an insulatingmaterial.
 4. The circuit breaker as claimed in claim 2, wherein theguide body is at least partially comprised of an insulating material.